Acoustical silencer



Feb. 10, 1959 T; TINKER ACOUSTICAI. SILENCER 2 Sheets-Sheet 1 FiledMarch 30, 1954 IIIIII I I II IIIIII/ I IIIIII II IIIIIIIII II IIII II IIIIII III III; I?

II IIIIII \N QM WN 4 ATTORNEYS.

United States Patent ACOUSHCAL SILENCER Townsend Tinker, Orchard Park,N. Y., assignor, by mesne assignments, to American Radiator & StandardSanitary Corporation, New York, N. Y., a corporation of DelawareApplication March 30, 1954, Serial No. 419,711

8 Claims. (Cl. 181-53) This invention relates to silencing devices andparticularly to devices of this class wherein a pulsating column of agaseous medium flowing in a conduit is subject to the sound attenuatinginfluence of the device by interposing the latter in the column ofpulsating gaseous medium whereby the gas flows through the device andits sound propagating propensities are to a great extent nullified oreliminated.

A well known class of gaseous conduit sound modifying devices comprisesa longitudinally elongated cylindrical casing having an intermediatetransverse baffle wall which divides the easing into two end-to-endcoaxial cylindrical chambers. The pulsating gas is introduced to one endof the cylindrical casing for entry into an inlet chamber and is passedtherefrom in a variety of ways to the opposed coaxial chamber whichcomprises an outlet chamwith respect to each other or with respect tothe point at which the incoming air is released into the entry portionof the cylindrical chamber.

Several practical embodiments of the principles of the present inventionare shown in the accompanying drawings and described in detail in thefollowing specifi cation. However, it is to be understood that thedetails and proportions thus shown and described are by way of exampleonly and that the scope of the invention is to be measured by theappended claims and is not limited excepting as defined in the claims.

In the drawings:

Fig. 1 is a general longitudinal cross-sectional view through one formof the acoustical silencer of the present invention;

Fig. 2 is a similar view through a modified form of the acousticalsilencer of the present invention; and

Fig. 3 is a transverse cross-sectional view on the line III-III of Fig.2.

Referring to the embodiment of the invention illustrated in Fig. 1, thenumeral 16* designates generally a cylindrical casing consisting of acentral tubular cylindrical body member 11 and end Walls or head members12 and 13. In the illustrated instance the end wall members 12 and 13are butt welded to body member 11 as at 14 and 15, respectively, andcircular backing strips 16 and 17 may be arranged at the inner sides ofthe butt her, from which the gas passes into a continuation of the is arather wide and unexplainable discrepancy between actual performance andthat which might be predicted from an application of the foregoingtheoretical considerations. In fact, actual performance of an acousticaldevice of this class seldom follows what might be expected or predictedfrom purely theoretical considerations.

Accordingly, it is difiicult to rationalize or explain from atheoretical standpoint the reasons why a given organization of elementsof this class produces a given result. In conceiving the acousticsilencer or silencers forming the subject matter of the presentinvention, I have found that certain constructions involving the passageof the gases from the inlet to the outlet chambers of acousticalsilencers of the type generally described above produced remarkablesoundattenuating results in welds to facilitate welding and reinforce thejoint.

The left-hand end of the present formof the invention comprises theentry end as viewed in Fig. 1 and an inlet pipe or conduit 20 is fixedcoaxially in end member 12, as by Welding, in such manner that asubstantial portion of inlet pipe 20 extends within the interior of thecasing 10. A circular transverse wall 21 is welded within cylindricalmember 11 substantially midway thereof to divide casing 10 intoapproximately equal inlet and outlet chambers.

It will be noted that inlet pipe 20 extends within the inlet chamber ofcasing 10 to a point approximately half way along the full diameterportion of the inlet chamber. The portion of inlet pipe 20 which extendswithin the inlet chamber is provided with longitudinal slots 23, in thepresent instance four in number.

Passage of gas from the inlet to the outlet chamber is by way of aseries of tubular members which are welded into transverse wall 21 andextend generally parallel to the axis of the cylindrical casing. In thepresent instance these tubes are four in number and are designated 26.

silencers of only a fraction of the size heretofore con- 1 siderednecessary to attain a given silencing result. It may be stated generallythat the efficacy of these cylindrical acoustical silencers generallyvaries with the volumetric size thereof.

In its broadest sense the present invention involves an acousticalsilencer having a pair of end-to-end cylindrical chambers and aplurality of tubular members passing through the dividing wall betweenthe charm-- bers, wherein the tubular members have entirely closed endsat their discharge portions whereby the gases fiowing from the entrychamber to the discharge chamber through the tubes discharge entirelythrough radial formations in the tubes. In addition, the presentinvention provides acousticalsilencers wherein the entry ends of thesetransverse tubes bear a particular relationship Each tube 26 begins atapproximately the plane of the inner end of the inlet pipe 20 andextends into the outlet chamber of casing 10 a distance which in thepresent instance is slightly greater than the length of the portion ofthe tube that is within the inlet chamber. In fact, as shown in Fig. lthe outlet portions of tubes 26 extend along a major part of the lengthof the outlet chamber.

The inlet ends of the tubes 26 are open but the outlet ends thereof areclosed, in the illustrated instancef'by means of discs 27 which may bewelded to the ends of the tubes 26. The outlet ends of the tubes 26 arethus completely closed and gas passing from the inlet chamber to theoutlet chamber of casing 10 through the tubes 26 discharges from thosetubes entirely through'longitudinal slots formed in the peripheries ofthe several tubes. These slots are designated 28 in Fig. l and in theillus trated instance there are eight slots for each time, the

. slots running substantially the full length of the portions of thetubes disposed within the outlet chamber.

The inlet portions of the tubes 26 are each provided,

asraees' f phase relationship to create a turbulence which contributesfurther to the anti-resonaut. .and sound dissipating effect ofthedevice, in a manner which is known to the art here involved. l

The .bell shaped end member 13 at the-outlet end of casing is providedwith an axial outletpipe 31, and inlet pipeltl and outlet pipe 31 mayboth be connected in circuit with a gas conduit by welding or by anysuitable coupling means.

1 In the modified form of the present invention illustrated in Figs. 2and 3 the basic feature of intermediate transfer tubes having closedoutlet ends is generally the samev as inthe previous embodiment but inthe embodiment of Figs. 2 and 3 the inletends of these transfer tubesare staggered along the length of the inlet-chamber portion ofthe devicein a manner which will presently appear.

Referring particularly to Fig. 2, theimodificati-Ou of the inventionthere shown comprises a cylindrical casing member 40 having a pair ofend head members 41 and 42 at its inlet and outlet ends, respectively.The head members 41 and 42 are provided with inlet and outlet pipes 43and 44 and, in the present instance, with flanges 45 and 46. forsecurement to conduits leading to and from the silencer. As in theprevious embodiment, the cylindrical space Within the casing member 40is divided substantially medially by a circular transverse wall 48. Aninlet tube 49 is fixed in the inlet end of the device and extends alongthe inlet chamber for a substantial portion of its-length. Inlet pipe 49is provided with a plurality of:longitudina1 slots inits, periphery, theslots being designated 50 inFig. 2' and, in the present instance,beingeight in number.

In the modification of Figs. 2 and 3 the transfer tubes which. are fixedin transverse wall 48 are circularlyv arranged as shown in Fig. 3 and inthe present instance are eightin number.

As shown in Fig. 3 the eight transfer an. entry. tube. extending. into,oneof said. chambers, from the end thereof remote from the otherchamber, a plurality of tubular members forming passages between thechambers, said tubular members having their axes ofiset from the axis ofsaid entry tube and each being disposed partly in each chamber andhaving an entry portion in said one chamber and adischarge portion insaid other chamber, the discharge portion of each tubular member havinga closed end and a plurality of lateral: discharge passages, saidlateral discharge passages providing; substantially the entire dischargepassage means from said tubular members.

2. A silencer, comprising a pair of adjoining chambers, an entry tubeextending into one of said chambers from the end thereof remote. fromthe other; chamber, a plurality of tubular members forming passagesbetween the chambers, said tubular members having their axes ofiset Yfrom the axis of, said'entry tube and each beinfgdistubes. are'numberedconsecutively 51 through 58. The 7 tubes 51 through 58 are of varyinglengths and as presently arranged the variations in length affect onlythe disposition of the inlet portions of the tubes, the outlet portionsbeing generally aligned in a common transverse plane.

A pair of diametrically opposed tubes 51 and 55 are p of greatest lengthat the entry end, a second pair of diametrically opposed tubes 52 and 56are of next greatest length, a third pair-0f tubes 54 and 58 are shorterthan the tubes 52 and 56 and in the present instance terminate at"aboutthe plane of the discharge endof inlet-tube 49. The fourth pair ofdiametrically opposed tubes 53 and 57 are shortestin length Byvirtue ofthe staggered arrangement of: the entry endsofthe' tubes'51 throughSS anumber of parallelfiow paths, of different lengthsare provided. Thisarrangement produces; gas flow discharge fromthe several tubes v whosepulsations are out of phase with each other, due totheir varying lengthsof travel betweenthetwo chambers. This staggered tube arrangement thuscooperateswith the other s l'l fllf a s the device of F g- 2of'the'pfesfint tubular members being disposed generally medially ofinvention; and contributes materially to the ultimate silencingefiiciency which is the primary aim of. the present invention.

Theoutlet ends ofsallof thetubes 51 through 58 are closed as by means ofdiscs fifliwhichmay be, welded in place as described in connection withthe, previousembodiment and, each of the tubes '51 through 58;. isprovided with lateral discharge orificesinthe formof longi': tudinal,slots: in, the peripheries. of the tubes, the slots being designated 61and extending throughout the major portions of;those:parts ofthetubes 51through 5.8 which extend. within; the outlet, chamberof. the casing. In;the present instance the slots- 61 of, each tube are; six;in,num: her;The entry, portions-of; the; tubes: 51 through 53' are provided; withperforations, 625 corresponding in. function posed partly ineach chamberand having an entry por; tion in said one chamber and' a dischargeportion in said other chamber, the discharge portion of each tubularmember having a closed end and a plurality of lateral dischargepassages, said lateral discharge passages pro.- viding substantially theentire discharge passage means from said tubular members, the inner endof said entry tube and the entry ends of. said tubular members beingdisposed generally -medially of said one chamber.

3; A silencer comprising a pair of adjoining chambers, agenerallycentral entry tube extendingjinto one of said chambers from the endthereof. remote from, the .other chamber, a, plurality. oftubular-members forming: pas..- sages between the. chambers, saidtubular, members being circularly arranged about saidentry tubewiththeir axes ofiset' from-theaxis of said entry-tube and eachbeiugdisposed partly in each chamber and having an entryxportion in said onechamber and a discharge portion in said other chamber, the. dischargevportion of each tubular member having a closed end and a plurality oflateral discharge passages, said lateral discharge passages pro vidingsubstantially the entire discharge passagemeans from said tubularmembers.

4; A silencer comprising a pair of adjoining chambers, a generallycentral entry tube extending into one of said chambers from the endthereof remote from the other chamber, a plurality of tubular membersforming passages between the chambers. said tubular members beingcircularly arranged about said entry tube-with their axes offset fromthe axis of said' entry tube and each being disposed partly in eachchamber and having an entry portion in said one chamber and a dischargeportion in said other chamber, the discharge portion of each tubularmember having a closed end and a said one chamber.

5. A silencer comprising a pair of adjoining chambers,- agenerallycentral entry tube extending into one of said chambers from the endthereof remote fromthe other chamber, said'entry tube having lateraldischarge passages t0;theperforations:30 of1the tubes -26'0f,.Fig. l,.

into said one chamber, a plurality of tubular members forming passagesbetween the chambers, said tubular members'being circularly arrangedabout said entry tube with their axes offsetfrom the axis of said entrytube and each being disposed partly in each chamber and having an entryportion in said one chamber and "a discharge portion in said otherchamber, the discharge portion ofeach tubularmember having a-ciosed'end' and a plurality of lateral discharge passages, saidlateral discharge passages providing substantially the entire dis+ charge passagemeans from said tubular members.

6. silencer-comprising a pair of adjoining chambers; a pluralityoftubular members forming passages betweenthe chambers, said tubularmembers each having an entry portion in one chamber and a dischargeportion in the other chamber, the entry portion of each tubular memherhaving an open end and the discharge portion of each tubular memberhaving a closed end, the entry ends of the tubular members beingstaggered along said one chamber, and the discharge portion of eachtubular member having a plurality of lateral discharge passages.

7. A silencer comprising a pair of adjoining chambers, a plurality oftubular members forming passages between the chambers, said tubularmembers each being disposed partly in each chamber and having an entryportion in one chamber and a discharge portion in the other chambet, theentry ends of the tubular members being disposed at various distancesalong said one chamber, the discharge portion of each tubular memberhaving a closed end and a plurality of lateral discharge passages, saidlateral discharge passages providing substantially the entire dischargepassage means from said tubular members.

8. A silencer comprising a pair of adjoining chambers, an entry tubeextending into one of said chambers at the end thereof remote from theother chamber, a plurality of tubular members forming passages betweenthe chambers, said tubular members each being disposed partly in eachchamber and having an entry portion in said one chamber and a dischargeportion in said other chamber, the entry ends of said tubular membersbeing disposed at various distances along said one chamber with some ofsaid entry ends ahead of and some behind the discharge end of said entrytube, the discharge portion of each tubular member having a closed endand a plurality of lateral discharge passages, said lateral dischargepassages providing substantially the entire discharge passage means fromsaid tubular members.

References Cited in the file of this patent UNITED STATES PATENTS779,024 Buchner et al. Jan. 3, 1905 2,033,784 Pougher et al Mar. 10,1936 2,166,670 Martin July 18, 1939 2,205,899 Chipley June 25, 19402,326,613 Bourne Aug. 10, 1943 2,416,452 Marx Feb. 25, 1947 2,624,418Bourne Jan. 6, 1953 FOREIGN PATENTS 514,944 France Nov. 19, 1920 747,943Germany Nov. 17, 1944

